Migrate from SkCanvas::getGrContext to SkCanvas::recordingContext

This is part of API cleanup as we make DDL usage more mainstream
in Skia. Since Android doesn't use DDLs, the cast from recordingContext
to directContext will always succeed and there's no functional change.

Change-Id: Ie585cf6c97d01fecf082f146d5692999371fd39d
5 files changed